State the reason for nixvim over LazyVim/NvChad — lazy.nvim fetches and updates plugins at runtime, putting the editor outside the flake — along with what that costs in ergonomics, and that borrowing a distro's keymaps and defaults into this file remains open. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_015D4NsszUG7hy9ghKZ4nfhm